Nanophase Separation in Monodisperse Rodcoil Diblock Polymers
Nanophase Separation in Monodisperse Rodcoil Diblock Polymers
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DOI：
10.1021/ma00104a033
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发表时间：
1994-12
期刊：
影响因子：
5.5
通讯作者：
L. Radzilowski;S. Stupp
中科院分区：
文献类型：
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作者：
L. Radzilowski;S. Stupp
作者在实验室合成的棒状线圈聚合物中观察到纳米相分离的结构。每种聚合物都由一个完全单分散的棒状链段组成，它与聚异戊二烯的线团状链段共价键合，从而使棒状和线团共享相同的分子骨架。聚异戊二烯是通过活性阴离子聚合制备的，因此在所研究的体系中，棒状线圈双嵌段分子的摩尔质量相当均匀。对大约5-10 nm厚的溶液浇铸薄膜进行热处理，可以得到有序的纳米级形貌，这取决于这些双嵌段分子中棒段的体积分数。作者用电子显微镜观察发现，随着棒材体积分数的降低，样品的形貌发生变化，从棒状和盘状磁畴交替排列的条状，到排列在六方超晶格中的离散棒状聚集体。在中等体积分数时，作者看到条状和集合体共存。棒状域的这种分裂可能是像Williams和Fredrickson最近在棒状线圈的层状组件中假设的那样的熵线圈拉伸惩罚的结果。
The authors have observed nanophase-separated structures in rodcoil polymers synthesized in their laboratory. Each polymer consists of a perfectly monodisperse, rodlike segment covalently bonded to a coil like segment of polyisoprene such that both rod and coil share the same molecular backbone. The polyisoprene was prepared by living anionic polymerization, and thus the rodcoil diblock molecules in the systems studied are of fairly uniform molar mass. Annealing of solution-cast thin films approximately 5--10 nm thick leads to ordered nanoscale morphologies that depend upon the volume fraction of rod segments in these diblock molecules. The authors find by transmission electron microscopy that the morphology varies from alternating strips of rod- and coil-rich domains to discrete aggregates of rods arranged in a hexagonal superlattice as rod volume fraction is decreased. At an intermediate volume fraction the authors see a coexistence of strips and aggregates. This breakup of rod domains may be the result of entropic coil stretching penalties analogous to those postulated recently by Williams and Fredrickson in lamellar assemblies of rodcoils.